Sewing-machine.



M. T. DENNE.

' SEWING MACHINE.

APPLICATION FILED MAYIB. 1914.

Patented Apr. 30,1918.

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M. T. DENNE.

SEWING MACHINE. APPLICATUION FILED MAYIS, 1914.

Patented. Apr. 30, 1918.

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MQTK T. Denne byi/malgwtlw Ill MARK THOMAS DENNE, 0F RUSHIDEN, ENGLAND.

rates la r lbw SEWING-MACHINE.

Specification of Letters Patent. Patented Apr 3t), ll llln Application filed May 18, 1914. Serial No. 839,209.

T is invention has reference to improvements in sewing machines in which the ten sion on the thread is automatically relieved when the machine stops and restored when the machine is again started.

The known tension-release devices have the serious detect that if the machine be started or stopped gradually, thetension is applied or released gradually, with the result that the first orlast few stitches are not properly drawn in, and the object of my invention is to insure that the thread tension device shall be put into action before the machine has been started and only released after the machine has been stopped.

With this object in view, my invention comprises, in a power-driven sewing machine which is started and stopped by moving a control "member, the combination with the'thread tension device of a tensionreleasing member which is actuated and controlled by the said control member in such a manner that the first portion of the movement of said control member in a direction to start the machine, but before themachine is started,causes said tension-releasing member to permit the tensioning of the thread, which tensioning is maintained during the whole time that the machine is in operation, and can only be released after the machine haseo'mpletely stopped.

In carrying my invention into practice, I provide a rod or the like, one end of which is attached to the usual starting treadle, which rod not only controls the movements of the driving clutch, but also controls the movements of the tension devicethrough the tension-releasing member in such a manner that the first portion of the movement of the treadle will put the thread-tensioning device into operation to grip the thread frictionally but without putting the driving clutch into operation, the latter being eitected only by the subsequent further movement of the treadle,

and, conversely, the first portion of the trea dle movement as it is being released will ef-.

feet the uncoupling or disengagement of the driving clutch but without putting the thread tensioning device out of aetion,the

latter being rendered inoperative only by the further and complete release of the treadle after the machine has already stopped.

I have illustrated my invention in the accompanying drawings in which Figures 1 and 2 show side and end elevations, re-.

spectively, of one form oi tension device and tension-releasing means, together with means for controllingfthe same in accordance with the invention, and Fig. 3 illustrates the application of the invention to one form of power driven sewing machine fitted with such a tension device and tension releasing means, such power driven machine being a conventional form and forming no part of the present invention, In carrying my invention into practiceI employ the ordinary control treadle V, the depression of which effects the cupling together of the ordinary friction clutch members T, U usually employed to drive the machine but with this difference that the connection between the treadle andthe usual wedge N or equivalent whereby the friction members are made to engage is such that the treadle may be de pressed for some distance against the action or the usual spring l i-before the wedge is made'to move.

This lost motion (so far asthe starting of the machine is concerned) of the treadle is made use of by me to put the threadten= sioning device into operation for whichpurpose I may employ the following meansand connections. ,The thread tensioning device may be the well known tension disks B, C and which I support between two friction disks 1), E, one of which latter E is carried by a bracket F on the machine frame and the other D of which is provided with a spindle G passing centrally through the tension disks and the other friction disk and extending some distance beyond the latter.

Surrounding a portion of the extending part of the spindle G' I provide a spring H one end of which acts against the bracket F re= ferred to and the other against an adjustable nut J on the spindle G whereby the tension of the spring H maybe adjusted, the spring normally serving to draw the friction disks 1), E, together to thereby frictionally grip mally serves to raise the rod and the treadle to their highest positions and between the top end of the said rod K and the rear end of the disk carrying spindle G I provide a bell crank lever L arranged in such a manner that when the rod is in its highest position it will have raised one arm m of the bell crank lever and thereby caused the other arm n of said lever to press back the spindle overcoming in doing so the tension of the spring H thereonand with the latter the friction disk D. carried thereby thus freeing the tension disks.

When the operator depresses the treadle the treadle rod K will. be pulled down thereby freeing the bell crank lever I1 and permitting the spring H referred to to bring about the frictional engagement of the tension disks B, C with the friction disks D, E.

In order to prevent the bell crank lever L rotating too far when the treadle rod K is pulled down I may interpose a. light spring 0 to support the bell crank lever in about its normal position and I may provide one arm (or may be both arms) of the bell crank lever with a set screw P to permit fine adjustment thereof relatively to the treadle, rod and to the friction disk spindle. The treadle rod K has a dog Q, secured upon it which in the stopping position (as shown in Fig. 3) is slightly separated from the end of a lever R that is connected at its other end to the usual clutch operating wedge W. vVhen the operator depresses the treadle V the initial down-- ward movement of the rod K will release the spring H so that the latter will apply the tension, as above described. During this initial movement the lost motion between the dog Q and the lever B is taken up so that when the tension has been applied, then during the further downward movement of the rod K, the dog Q will act on the lever R and thereby operate the latter to cause the clutch-operating wedge W to force the thrust block S into contact with the driving member T of the clutch and to move the same along the driving shaft into contact with the clutch member U thereby to start the machine. When the rod K is moved in the reverse direction the initial move- 'ment thereof will result in permitting the the machine is started, but is not released until after the machine has been brought to rest.

I wish it however to be understood that I do not limit the scope of my invention to the particular mechanism described for controlling the tension device nor to the particular device described.

In addition to the usual driving means for example a friction clutchI may provide any known means whereby so soon as the friction clutch is thrown out of action, the machine is brought substantially instantly to a top. I

What I claim as my invention and des re to secure by Letters Patent is 1.111 a power driven sewing machine, the combination with a control member, of a reciprocable clutch-operating element operated by the control member, a thread tension device, and a tension-releasing member which is interposed between said control. member and the tension device so that reciprocating movement of the control member will operate to release and apply the tension, said control member being adapted to release the tension only after the machine has been stopped and to permit the tension to be automatically applied before th machine can be restarted.

2. In a power driven sewing machine. the combination with a clutch for actuating said machine, of a control member, a recipro cable clutch-operating element connected to the control member to be actuated thereby, a thread tension device, means for auto-- matically applying the tension. means in terposed between the clutch-operating clc ment and the clutch by which the clutch is applied during the final movement of said element in one direction and is released during the initial movement of said element in the opposite direction, and means interposed between said element and the tension device whereby the tension will he applied during the initial movement of said element in the first-named direction and will be released during the final movcnnnt of said element in the opposite direction whereby the tension will only be released after the clutch has been disconnected and will always be applied before the clutch is thrown into operation.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

MARK THOMAS DENNIS.

Witnesses WALTER W. BALL, F. HOOD.

Cople: of this patent may be obtained for five cents each. by addressing the Commissioner of Patents. Washington, D. C. 

